1. Field of the Invention
The present invention relates to a resilient ball joint support which, when it is interposed between a mobile load and a structure supporting this load, provides both absorption of energy at the time of placing the load and a nutational freedom of movement of the load with respect to the load supporting structure.
Generally, the resilient ball joint support of the present invention is applied to supporting and handling heavy loads which must remain nutationally mobile with respect to their support structure. It is more particularly adapted to use on ships or sea platforms, for suspending swinging loads, for example, or equipment connected to the bottom of the sea, when the support structure is subjected to the movements of the swell.
2. Description of the Prior Art
Support structures are already known allowing a freedom of movement of the load in nutation, such as ball joint shoes, in sliding contact between two spherical surfaces, or such as spherical stratified rubber or metal stops.
Stratified spherical stops of this type are described for example in French Pat. Nos. 80/15 454 and 2.370. 900.
This freedom of movement is obtained in this case at the cost of high angular stiffness of the system, resulting either from a coefficient of friction difficult to reduce or from the rigidity under shearing of the elastomer plates which must have a sufficient area for supporting heavy loads.
These systems in addition do not provide energy absorption at the time of setting down the load.
A more improved system exists, described, for example, in the U.S. Pat. No. 3 984 990, which results from the association of a ball joint with a series of actuating cylinders disposed about a circle concentric with the ball joint and whose chambers are caused to intercommunicate by connecting pipe means.
Such a system provides absorption of energy at the time when the load is set down, but has the drawback of requiring a large number of precise mechanical parts, subject to wear and to corrosion and requiring constant maintenance. For supporting heavy loads it requires the use of very high hydraulic pressures and, ensuring the pinpoint transmission of loads, produces high local force concentrations in line with the cylinder fastenings.
On the other hand, the device of the invention allows the heavy loads to be absorbed over a large area with a relatively low fluid pressure, and with the major parts of its components, made from flexible materials, being insensitive to corrosion, wear and fatigue and require no maintenance.